Method of preparing graft polymer

Abstract

The present disclosure relates to a method of preparing a graft polymer, which includes: performing primary continuous polymerization by adding a diene-based rubber polymer and an aromatic vinyl-based monomer to a first reactor; and performing secondary continuous polymerization by adding the polymerization product discharged from the first reactor, a maleimide-based monomer, and a vinyl cyanide-based monomer to a second reactor.

The invention claimed is: 
     
         1 . A method of preparing a graft polymer, comprising:
 performing primary continuous polymerization by adding a diene-based rubber polymer and an aromatic vinyl-based monomer to a first reactor; and   performing secondary continuous polymerization by adding the polymerization product discharged from the first reactor, a maleimide-based monomer, and a vinyl cyanide-based monomer to a second reactor,   wherein the adding of the polymerization product, the maleimide-based monomer, and the vinyl cyanide-based monomer starts when a polymerization conversion rate reaches 25 to 35%.   
     
     
         2 . The method of  claim 1 , wherein the maleimide-based monomer is added in a dissolved state in the vinyl cyanide-based monomer. 
     
     
         3 . The method of  claim 2 , wherein a weight ratio of the maleimide-based monomer and the vinyl cyanide-based monomer is 15:85 to 25:75. 
     
     
         4 . The method of  claim 1 , wherein an amount of the maleimide-based monomer added in the secondary continuous polymerization is 1 to 10 parts by weight with respect to 100 parts by weight, in total, of the diene-based rubber polymer, the aromatic vinyl-based monomer, the maleimide-based monomer, and the vinyl cyanide-based monomer added in the preparing of the graft polymer. 
     
     
         5 . The method of  claim 1 , wherein an amount of the vinyl cyanide-based monomer added in the secondary continuous polymerization is 15 to 27 parts by weight with respect to 100 parts by weight, in total, of the diene-based rubber polymer, the aromatic vinyl-based monomer, the maleimide-based monomer, and the vinyl cyanide-based monomer added in the preparing of the graft polymer. 
     
     
         6 . The method of  claim 1 , wherein an amount of the diene-based rubber polymer added in the primary continuous polymerization is 7 to 17 parts by weight with respect to 100 parts by weight, in total, of the diene-based rubber polymer, the aromatic vinyl-based monomer, the maleimide-based monomer, and the vinyl cyanide-based monomer added in the preparing of the graft polymer. 
     
     
         7 . The method of  claim 1 , wherein an amount of the aromatic vinyl-based monomer added in the primary continuous polymerization is 55 to 67 parts by weight with respect to 100 parts by weight, in total, of the diene-based rubber polymer, the aromatic vinyl-based monomer, the maleimide-based monomer, and the vinyl cyanide-based monomer added in the preparing of the graft polymer. 
     
     
         8 . The method of  claim 1 , wherein the diene-based rubber polymer is added in a dissolved state in the aromatic vinyl-based monomer. 
     
     
         9 . The method of  claim 1 , wherein the diene-based rubber polymer is one or more selected from the group consisting of a butadiene rubber polymer and a styrene-butadiene rubber polymer. 
     
     
         10 . The method of  claim 1 , wherein the primary and secondary continuous polymerizations are each a continuous bulk polymerization.